Phosphate

When low (hypophosphatemia):

Dietary management:

• Increase phosphate-rich foods: dairy, meat, fish, eggs, nuts, seeds, legumes
• Athletes on high-protein diets rarely have low phosphate; if present, investigate refeeding syndrome (after prolonged caloric restriction in contest prep), Vitamin D deficiency (impairs phosphate absorption), or antacid overuse (binds phosphate in the gut)

Supplements:

• Usually dietary correction is sufficient
• Vitamin D3 -- 5000 IU/day if Vitamin D is low (Vitamin D drives phosphate absorption)

When high (hyperphosphatemia):

• Rare without kidney dysfunction -- check eGFR and creatinine
• Reduce phosphate-rich processed foods and carbonated drinks (phosphoric acid)
• If kidney function is impaired, dietary phosphate restriction is important
• Ensure adequate calcium intake (calcium and phosphate are regulated in balance)

References:

• Holick, M. F. (2007). Vitamin D deficiency. New England Journal of Medicine, 357(3), 266-281. DOI: 10.1056/NEJMra070553
• Yao, P., Bennett, D., Mafham, M., et al. (2019). Vitamin D and calcium for the prevention of fracture. JAMA Network Open, 2(12), e1917789. DOI: 10.1001/jamanetworkopen.2019.17789